Hydrochloric solution

All the starting materials were obtained from commercial supplies and used as received. Rare-earth oxides Lu₂O₃ (99.999%), Yb₂O₃ (99.999%), Er₂O₃ (99.999%), and Tm₂O₃ (99.99%) were purchased from Beijing Lansu Co. Ltd. RECl₃ (RE³⁺ = Lu³⁺, Yb³⁺, Er³⁺, Tm³⁺) was prepared by dissolving the corresponding metal oxide in hydrochloric acid at elevated temperature then removed the solvent. Ethanol, cyclohexane, toluene, and hydrochloric solution were purchased from Sinopharm Chemical Reagent Co. China. Oleic acid (OA) (>90%) and 1-octadecene (ODE) were purchased from Aldrich. CsOH∙H₂O was purchased from Alfa Aesar Ltd. Indocyanine green (ICG) were purchased from TCI Chemical Reagent Shanghai Co. Ltd. Alpha-tocopheryl succinate (α-TOS) and N-hydroxysuccinimide sodium salt (sulfo-NHS) were purchased from Sigma (St. Louis, MO). DSPE-PEG (2000) maleimide and DSPE-PEG (2000) amino were purchased from Avanti. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) was purchased from Aladdin Reagent Co. Ltd. All the other chemical reagents were of analytical grade and were used directly without further purification. Deionized water was used throughout.

All the chemicals used were of analytical
purity without further purification. Diethylene glycol (DEG), hydrochloric
solution, NaOH, toluene, NH₄F, ethanol, methanol, cyclohexane,
OA, and formic acid were bought from Sinopharm Chemical Reagent Co.
PAA, rare earth oxides [Y₂O₃, Yb₂O₃, and Er₂O₃ are all of the same
purity grade (99.999%)], and 1-octadecene (ODE) were bought from Aladdin.
Rare earth chlorides (LnCl₃, Ln: Y, Yb, Er) were synthesized
according to the literature.^{36 (link)} PMMA (M_w = 20 000 000 g/mol) was purchased
from Asahi Kasei. PA6 (M_w = 40 000
g/mol) was purchased from DuPont.